Insulated rail joints

ABSTRACT

A rail joint bar moulded as a solid component from a reinforced dielectric material, to finished cross-sectional shape and overall dimensions. The bar is shaped and dimensioned to include surfaces which tighten in a wedging action against the head and flange of a rail when bolted to the rail. A pair of the bars are secured on opposite sides of the rail web to form a rail joint, with the bars clear of the rail web by virtue of their engagement with the head and flanges of the rail, thus ensuring that the pair of bars move with the rail during service and retain their clamped position at all times.

United States Patent Sinfield Oct. 7, 1975 [5 INSULATED RAIL JOINTS3,335,954 8/1967 Hamilton, Jr. 238/159 [75] Inventor: Kenneth StanleySinfield, Strathfield 1/1969 eckert 8/243 I es Us Ta la PrimaryExaminer-M. Henson Wood, Jr.

[73] A gn National pri g Limited, Assistant ExaminerRichard A. BertschAleXandfla, Australia Attorney, Agent, or Firm-Waters, Schwartz & Nissen[22] Filed: Oct. 4, 1973 Appl. No.: 403,623

[ 57] ABSTRACT A rail joint bar moulded as a solid component from areinforced dielectric material, to finished crosssectional shape andoverall dimensions. The bar is shaped and dimensioned to includesurfaces which tighten in a wedging action against the head and flangeof a rail when bolted to the rail.

A pair of the bars are secured on opposite sides of the rail web to forma rail joint, with the bars clear of the rail web by virtue of theirengagement with the head and flanges of the rail, thus ensuring that thepair of bars move with the rail during service and retain their clampedposition at all times.

1 Claim, 7 Drawing Figures us. Patent 0. 7,19 5, sheetlofg 3,910,492

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US. Patent Oct. 7,1975 Sheet 2 of? 3,910,492

US. Patent (M11975 Sheet 3 of3 3,910,492

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FIG. 7

INSULATED RAIL JOINTS This invention relates to improvements ininsulated rail joints and more particularly to insulated rail joint bars(fish plates) which are moulded a solid component from a reinforceddielectric material.

The invention also relates to a method of forming such rail joints usinga pair of rail jointbars according to the invention secured to oppositesides of the webs of two rails, by bolts or similar clamping devices.

When forming insulated rail joints using steel fish plates, it has beengeneral practice to interpose a layer of insulating material, whether asa separate piece or pieces or whether as an integral part of anassembly, between the fish plates and the rail which would otherwiseengage each other, and also to insulate the bolts from the rail by alayer of insulating material, whether as a separate piece or pieces orwhether as an integral part of an assembly, around the shanks of thebolts.

In this known technique, it has been found generally that the failure ofsuch insulated rail joints occurs by a breakdown at the insulatingsurfaces either as a result of gradual wear or abrasion of such surfacesdue to relative movement between the fish plates and the rail under theaction of service loads or as a result of fatigue of the insulatinglayers under the action of stresses imposed by service loads. Also waterabsorption of the insulating layers has been found to materiallyincrease the breakdown of these layers under service conditions.

In order to overcome electric failures of insulated rail joints whetherusing the known moulded dielectric bars or resulting from the failure ofsuch insulating layers used in conjunction with steel fish plates, thepresent invention proposes the use of joint bars manufactured in such away from a solid insulating or dielectric material so as to reduce thepossible modes of failure to only that of a complete physical ormechanical rupture of the joint bars themselves.

According to the invention, the rail joint bar is moulded a solidcomponent from a reinforced dielectric material to finishedcross-sectional profile shape and overall dimensions and has a pluralityof longitudinally spaced bolt holes formed therethrough. The bar ismoulded from a thermosetting glass filament reinforced material havingstrands of the glass filament reinforcement running longitudinally ofthe bar and disposed in random spacing throughout the bar crosssection.The bar includes top and bottom surfaces adapted to respectively engagethe under surface of a rail head and the upper surface of the railflange when mounted upon the rail and is dimensioned to tighten in awedging action against said rail surfaces when bolted to the rail.

Also according to the invention, a rail joint is formed by securing apair of the rail joint bars to opposite sides ofa rail web, the pair ofbars being bolted to the rail web with the top and bottom surfaces ofthe bar respectively engaging the under surface of the rail head and theupper surface of the rail flange, with the bar clear of the rail web.

The invention will now be described with reference to the accompanyingdrawings, wherein:

FIG. 1 is a perspective of the rail joint bar, looking from one end ofthe bar and at the vertical outer surface thereof.

FIG. 2 is an elevational view of the bar looking at the vertical outersurface thereof.

FIG. 3 is a similar view to FIG. 2 but looking at the opposite (inner)surface of the bar.

FIGS. 4, 5 and 6 are sectional views taken on the planes 44, 55 and 6-6of FIG. 2 and FIG. 7 is an end view of an assembly of a pair of the barsof the invention upon a rail.

In the illustrated embodiment, the bar is moulded to the finishedprofile shape and overall dimensions from a reinforced plastics materialand has a plurality of longitudinally spaced bolt holes 2 formedtherethrough either during the moulding operation or subsequently. Nomachine operations are required to produce the desired cross-sectionalshape on the bar 1 and thus the continuity of the reinforcement ismaintained in the areas between and surrounding the bolt holes 2. Thecross-sectional shape of the bar is such that when mounted on a rail Ras a pair, the bars engage the downwardly inwardly tapered under surfaceof the rail head H and the upwardly inwardly tapered upper surface ofthe rail flange F. Thus, when the pair of bars 1 are clamped to the railby the clamping bolts B, they tighten in a wedging action between thesurfaces referred to and they are clear of the rail web W. This ensuresthat the pair of bars 1 so clamped, tend to move with the rail R duringservice and retain their clamped positions at all times.

The cross-sectional profile of the bar 1 comprises a flat, verticalouter surface 3 blended by radiussed corners 4 into top and bottomsurfaces. The top surface extends upwardly inwardly as at 5 from theupper radiussed comer 4 for a short distance and then downwardlyinwardly as at 6 and the downwardly inwardly extending part 6 engagesthe under surface of the rail head. The bottom surface extends upwardlyinwardly from the lower corner 4 as at 7 and engages the upper surfaceof the rail flange. The lower corner 4 is chamfered at 8 at the endregions of the bar 1.

The chamfers 8 provide clearance for the heads of dogspikes which arefixed in conventional manner for securing a rail to sleepers, a featurenot found on other known joints of the type referred to with whichconventional dogspikes and other known fasteners cannot be used.

The downwardly inwardly extending part 6 of the top surface and thebottom surface 7 are blended by suitable radiussed projections 9, into apair of flat, vertical inner surfaces 10 which are set back from theprojections 9 towards the outer surface 3, on each side of a centreregion 11 of bar 1 which includes region 12 surrounding those bolt holes2 (centre bolt holes), located in region 12, and the vertical, innersurface 11-12 extends to the full width of the bar 1.

A pair of steel plates 13 are bonded to the vertical outer surface 3over the bolt holes 2 and they have bolt holes 14 formed therethroughregistering with the bolt holes 2 in the bar 1. The steel plates areseparated longitudinally from each other in the centre region 11 tomaintain the insulating properties of a joint assembly of the bars 1 andthey serve to distribute bolt clamping loads through the joint.

The bar 1 is moulded from a thermosetting polymer such as epoxide orunsaturated polyester resin, it is heavily reinforced with glassfilaments. The filaments run longitudinally of the bar and they aredisposed in random spacing throughout the bar cross-section. The use ofa thermosetting resin of the type referred to, reinforced in the mannerdescribed, provides in the fi'ri ished bar, the necessary mechanicalproperties capable of withstanding the stresses induced by boltv tensionthrough the joint bars when installed and stresses resulting fromfluctuating bending loads applied by traffic to the rails to which thejoints are secured, as well as those stresses induced by rail expansionand contraction due to temperature changes.

However, it is to be understood that the invention is not restricted tothermosetting resins of the type referred to. Developments in theplastics industry may produce other materials capable ofproviding'thcrequired properties in the joint, from which the joint canbe 'moulded at a cost consistent with the cost of the joint asdescribed.

I claim:

1. A rail joint bar moulded as a solid component from a reinforceddielectric material, said bar being moulded to finished cross-sectionalprofile shape and overall dimensions and having a plurality oflongitudinally spaced bolt holes formed therethrough, said bar beingmoulded from a thermosetting, glass filament reinforced material havingstrands of the glass filament reinforcement running longitudinally ofthe bar and disposed in random spacing throughout the bar crosssection,said bar including top and bottom surfaces adapted to respectivelyengage the under surface of a rail head and the upper surface of therail flange when mounted upon the rail and being dimensioned to tightenin a wedging action against said rail surfaces when bolted to the rail,the cross-sectional profile of the bar comprising a flat, vertical outersurface blended; by upper and lower radiussed corners into top and bot-.tom surfaces, 7 the top surface extending upwardly in-l wardly from theupper radiussed corner and then outer'surface and located on each sideof a center inner vertical surface extending to the full width of thebar,

said center inner vertical surface being located in a center--region ofthe bar and including regions surlrounding those said bolt holes locatedin this region, a pair of steel plates bonded tothe vertical outersurface of the bar and separated longitudinally from each other in saidcenter region of the bar, said steel plates having bolt holes formedtherethrough in registerwith the bolt holes in the bar; thelowerradiussed corner of the bar 7 being chamfered at each end region ofthe bar beneath the respective steel plates.

1. A rail joint bar moulded as a solid component from a reinforceddielectric material, said bar being moulded to finished cross-sectionalprofile shape and overall dimensions and having a plurality oflongitudinally spaced bolt holes formed therethrough, said bar beingmoulded from a thermosetting, glass filament reinforced material havingstrands of the glass filament reinforcement running longitudinally ofthe bar and disposed in random spacing throughout the bar cross-section,said bar including top and bottom surfaces adapted to respectivelyengage the under surface of a rail head and the upper surface of therail flange when mounted upon the rail and being dimensioned to tightenin a wedging action against said rail surfaces when bolted to the rail,the cross-sectional profile of the bar comprising a flat, vertical outersurface blended by upper and lower radiussed corners into top and bottomsurfaces, the top surface extending upwardly inwardly from the upperradiussed corner and then downwardly inwardly and the downwardlyinwardly extending part engages the rail head under surface; the bottomsurface extending upwardly inwardly from the lower radiussed corner andengaging the rail flange upper surface; the downwardly inwardlyextending top surface part and the bottom surface part being blended byradiussed projections into a pair of flat vertical inner surfaces setback from the projections towards the outer surface and located on eachside of a center inner vertical surface extending to the full width ofthe bar, said center inner vertical surface being located in a centerregion of the bar and including regions surrounding those said boltholes located in this region, a pair of steel plates bonded to thevertical outer surface of the bar and separated longitudinally from eachother in said center region of the bar, said steel plates having boltholes formed therethrough in register with the bolt holes in the bar;the lower radiussed corner of the bar being chamfered at each end regionof the bar beneath the respective steel plates.